As shown in FIGS. 17 and 18, in an analyzer 9, for example, a test piece 92 placed at a placing portion 91 of a table 90 is transferred to a photometry mechanism 93 so that the sample is analyzed based on the measurements by the photometry mechanism 93 (see Patent Document 1, for example). The photometry mechanism 93 includes light emitting elements 95 and light receiving elements 96 held by a case 94. The case 94 includes a lower opening 97 covered by a transparent plate 98.
The light emitted from the light emitting elements 95 and the light reflected at a reagent pad 99 of the test piece 92 are supposed to pass through the transparent plate 98. However, when the surface 98a of the transparent plate 98 is dirty, the light is absorbed or reflected at the transparent plate 98. In light of this, it is desirable to frequently clean the surface 98a of the transparent plate 98.
In the analyzer 9, to prevent the light receiving elements 96 from receiving external light, the distance between the upper surface 90a of the table 90 and the surface 98a of the transparent plate 98 of the photometry mechanism 93 is set to be small, and the photometry mechanism 93 is located at a back portion of the analyzer. In such an arrangement, the cleaning of the transparent plate 98 is performed, with the clearance between the photometry mechanism 93 and the table 93 being lit with a flashlight, by inserting a cotton swab wet with a cleaning liquid into the clearance and rubbing the transparent plate 98 with the swab. As readily seen, the cleaning of the transparent plate 98 is not easy. Accordingly, the user may neglect the cleaning of the transparent plate 98, thinking of the difficulty of the operation. As a result, the reliability of the analysis deteriorates. Further, since the transparent plate 98 is not within easy access and the cleaning is performed manually, it depends on users how well the cleaning is finished. Unfavorably this dependency results in the difference in the analysis accuracy.    Patent Document 1: Japanese patent No. 2561509